The invention relates to a weighing system that works on the principle of electromagnetic force compensation. The weighing system has two guide members that act as a parallel guide unit and connect a load support to a base region that is fixed to a housing. The weighing system also has at least one transmission lever, which has lever arms of different lengths, supported on the base region. The weight force of a load to be weighed is transmitted by a load support, and the force is applied to the shorter lever arm of the transmission lever via a coupling element. The longer lever arm is secured to a coil that protrudes into an air gap of a permanent magnet system.
A weighing system as described above is disclosed in the German patent specification DE 32 43 350 C2. In the weighing system described in DE 32 43 350 C2, the transmission lever, the permanent magnet system and the coil are located in an area that is within the parallel guide unit (i.e., within the base region, the load support and the two guide members). However, if this system is made narrower, the length of the transmission lever and the space available for the permanent magnet system would be very limiting.
A similar system is disclosed in the European publication EP 0 291 258 A2. In EP 0 291 258 A2, the base region of the weighing system is configured as two subregions that are interconnected by spacers. However, this configuration would also limit the length of the lever and the space available for the permanent magnet system.
To avoid this drawback, EP 518 202 A1 discloses a design in which the transmission lever is guided laterally along both sides adjacent to the base region by extending the lever using two braces. EP 518 202 A1 also discloses a design that disposes the coil and the permanent magnet system on the other side of the base region—i.e., outside the parallel guide unit.
A similar system is disclosed in DE 100 15 311 A1. In DE 100 15 311 A1, however, the transmission lever is guided along only one side of the base region. Thus, the design is not symmetrical with respect to the base region.
However, in the above systems, the lateral braces of the transmission lever extension will interfere if a plurality of weighing systems is arranged side by side. Therefore, the weighing systems cannot be arranged laterally in a row as tightly spaced as possible, and the lateral distance between two weighing system cannot be minimized to a desired extent. For example, if the body of the system formed by the base region, the guide members, the load support and the transmission lever is 10 mm wide, the braces to extend the transmission lever are 2 mm wide and a lateral play of 0.5 mm each is required, the distance between two weighing systems cannot be made smaller than 15.5 mm.